def is_prime(n):
    for i in range(2, int(n**0.5)+1):
        if n % i == 0:
            return False
    return True
n = int(input())
if n < 2:
    print("判断结束！")
elif is_prime(n):
    print(f"{n}是素数")
else:
    print(f"{n}不是素数")
